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Main functionality for HBase
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hbase.io.hfile;
import java.io.DataInput;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.KeyValue.KVComparator;
import org.apache.hadoop.hbase.NoTagsKeyValue;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.fs.HFileSystem;
import org.apache.hadoop.hbase.io.FSDataInputStreamWrapper;
import org.apache.hadoop.hbase.io.encoding.DataBlockEncoder;
import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
import org.apache.hadoop.hbase.io.encoding.HFileBlockDecodingContext;
import org.apache.hadoop.hbase.io.hfile.HFile.FileInfo;
import org.apache.hadoop.hbase.regionserver.KeyValueScanner;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.IdLock;
import org.apache.hadoop.io.WritableUtils;
import org.apache.htrace.Trace;
import org.apache.htrace.TraceScope;
import com.google.common.annotations.VisibleForTesting;
/**
* {@link HFile} reader for version 2.
*/
@InterfaceAudience.Private
public class HFileReaderV2 extends AbstractHFileReader {
private static final Log LOG = LogFactory.getLog(HFileReaderV2.class);
/** Minor versions in HFile V2 starting with this number have hbase checksums */
public static final int MINOR_VERSION_WITH_CHECKSUM = 1;
/** In HFile V2 minor version that does not support checksums */
public static final int MINOR_VERSION_NO_CHECKSUM = 0;
/** HFile minor version that introduced pbuf filetrailer */
public static final int PBUF_TRAILER_MINOR_VERSION = 2;
/**
* The size of a (key length, value length) tuple that prefixes each entry in
* a data block.
*/
public final static int KEY_VALUE_LEN_SIZE = 2 * Bytes.SIZEOF_INT;
private boolean includesMemstoreTS = false;
protected boolean decodeMemstoreTS = false;
protected boolean shouldIncludeMemstoreTS() {
return includesMemstoreTS;
}
/** Filesystem-level block reader. */
private HFileBlock.FSReader fsBlockReader;
/**
* A "sparse lock" implementation allowing to lock on a particular block
* identified by offset. The purpose of this is to avoid two clients loading
* the same block, and have all but one client wait to get the block from the
* cache.
*/
private IdLock offsetLock = new IdLock();
/**
* Blocks read from the load-on-open section, excluding data root index, meta
* index, and file info.
*/
private List loadOnOpenBlocks = new ArrayList();
/** Minimum minor version supported by this HFile format */
static final int MIN_MINOR_VERSION = 0;
/** Maximum minor version supported by this HFile format */
// We went to version 2 when we moved to pb'ing fileinfo and the trailer on
// the file. This version can read Writables version 1.
static final int MAX_MINOR_VERSION = 3;
/** Minor versions starting with this number have faked index key */
static final int MINOR_VERSION_WITH_FAKED_KEY = 3;
HFileContext hfileContext;
/**
* Opens a HFile. You must load the index before you can use it by calling
* {@link #loadFileInfo()}.
*
* @param path Path to HFile.
* @param trailer File trailer.
* @param fsdis input stream.
* @param size Length of the stream.
* @param cacheConf Cache configuration.
* @param hfs
* @param conf
*/
public HFileReaderV2(final Path path, final FixedFileTrailer trailer,
final FSDataInputStreamWrapper fsdis, final long size, final CacheConfig cacheConf,
final HFileSystem hfs, final Configuration conf) throws IOException {
super(path, trailer, size, cacheConf, hfs, conf);
this.conf = conf;
trailer.expectMajorVersion(getMajorVersion());
validateMinorVersion(path, trailer.getMinorVersion());
this.hfileContext = createHFileContext(fsdis, fileSize, hfs, path, trailer);
HFileBlock.FSReaderImpl fsBlockReaderV2 =
new HFileBlock.FSReaderImpl(fsdis, fileSize, hfs, path, hfileContext);
this.fsBlockReader = fsBlockReaderV2; // upcast
// Comparator class name is stored in the trailer in version 2.
comparator = trailer.createComparator();
dataBlockIndexReader = new HFileBlockIndex.BlockIndexReader(comparator,
trailer.getNumDataIndexLevels(), this);
metaBlockIndexReader = new HFileBlockIndex.BlockIndexReader(
KeyValue.RAW_COMPARATOR, 1);
// Parse load-on-open data.
HFileBlock.BlockIterator blockIter = fsBlockReaderV2.blockRange(
trailer.getLoadOnOpenDataOffset(),
fileSize - trailer.getTrailerSize());
// Data index. We also read statistics about the block index written after
// the root level.
dataBlockIndexReader.readMultiLevelIndexRoot(
blockIter.nextBlockWithBlockType(BlockType.ROOT_INDEX),
trailer.getDataIndexCount());
// Meta index.
metaBlockIndexReader.readRootIndex(
blockIter.nextBlockWithBlockType(BlockType.ROOT_INDEX),
trailer.getMetaIndexCount());
// File info
fileInfo = new FileInfo();
fileInfo.read(blockIter.nextBlockWithBlockType(BlockType.FILE_INFO).getByteStream());
byte[] creationTimeBytes = fileInfo.get(FileInfo.CREATE_TIME_TS);
this.hfileContext.setFileCreateTime(creationTimeBytes == null? 0:
Bytes.toLong(creationTimeBytes));
lastKey = fileInfo.get(FileInfo.LASTKEY);
avgKeyLen = Bytes.toInt(fileInfo.get(FileInfo.AVG_KEY_LEN));
avgValueLen = Bytes.toInt(fileInfo.get(FileInfo.AVG_VALUE_LEN));
byte [] keyValueFormatVersion =
fileInfo.get(HFileWriterV2.KEY_VALUE_VERSION);
includesMemstoreTS = keyValueFormatVersion != null &&
Bytes.toInt(keyValueFormatVersion) ==
HFileWriterV2.KEY_VALUE_VER_WITH_MEMSTORE;
fsBlockReaderV2.setIncludesMemstoreTS(includesMemstoreTS);
if (includesMemstoreTS) {
decodeMemstoreTS = Bytes.toLong(fileInfo.get(HFileWriterV2.MAX_MEMSTORE_TS_KEY)) > 0;
}
// Read data block encoding algorithm name from file info.
dataBlockEncoder = HFileDataBlockEncoderImpl.createFromFileInfo(fileInfo);
fsBlockReaderV2.setDataBlockEncoder(dataBlockEncoder);
// Store all other load-on-open blocks for further consumption.
HFileBlock b;
while ((b = blockIter.nextBlock()) != null) {
loadOnOpenBlocks.add(b);
}
// Prefetch file blocks upon open if requested
if (cacheConf.shouldPrefetchOnOpen()) {
PrefetchExecutor.request(path, new Runnable() {
public void run() {
long offset = 0;
long end = 0;
try {
end = getTrailer().getLoadOnOpenDataOffset();
HFileBlock prevBlock = null;
if (LOG.isTraceEnabled()) {
LOG.trace("Prefetch start " + getPathOffsetEndStr(path, offset, end));
}
while (offset < end) {
if (Thread.interrupted()) {
break;
}
// Perhaps we got our block from cache? Unlikely as this may be, if it happens, then
// the internal-to-hfileblock thread local which holds the overread that gets the
// next header, will not have happened...so, pass in the onDiskSize gotten from the
// cached block. This 'optimization' triggers extremely rarely I'd say.
long onDiskSize = prevBlock != null? prevBlock.getNextBlockOnDiskSize(): -1;
HFileBlock block = readBlock(offset, onDiskSize, true, false, false, false,
null, null);
prevBlock = block;
offset += block.getOnDiskSizeWithHeader();
}
} catch (IOException e) {
// IOExceptions are probably due to region closes (relocation, etc.)
if (LOG.isTraceEnabled()) {
LOG.trace("Prefetch " + getPathOffsetEndStr(path, offset, end), e);
}
} catch (NullPointerException e) {
LOG.warn("Stream moved/closed or prefetch cancelled?" +
getPathOffsetEndStr(path, offset, end), e);
} catch (Exception e) {
// Other exceptions are interesting
LOG.warn("Prefetch " + getPathOffsetEndStr(path, offset, end), e);
} finally {
PrefetchExecutor.complete(path);
}
}
});
}
}
protected HFileContext createHFileContext(FSDataInputStreamWrapper fsdis, long fileSize,
HFileSystem hfs, Path path, FixedFileTrailer trailer) throws IOException {
return new HFileContextBuilder()
.withIncludesMvcc(this.includesMemstoreTS)
.withCompression(this.compressAlgo)
.withHBaseCheckSum(trailer.getMinorVersion() >= MINOR_VERSION_WITH_CHECKSUM)
.build();
}
private static String getPathOffsetEndStr(final Path path, final long offset, final long end) {
return "path=" + path.toString() + ", offset=" + offset + ", end=" + end;
}
/**
* Create a Scanner on this file. No seeks or reads are done on creation. Call
* {@link HFileScanner#seekTo(byte[])} to position an start the read. There is
* nothing to clean up in a Scanner. Letting go of your references to the
* scanner is sufficient.
*
* @param cacheBlocks True if we should cache blocks read in by this scanner.
* @param pread Use positional read rather than seek+read if true (pread is
* better for random reads, seek+read is better scanning).
* @param isCompaction is scanner being used for a compaction?
* @return Scanner on this file.
*/
@Override
public HFileScanner getScanner(boolean cacheBlocks, final boolean pread,
final boolean isCompaction) {
if (dataBlockEncoder.useEncodedScanner()) {
return new EncodedScannerV2(this, cacheBlocks, pread, isCompaction,
hfileContext);
}
return new ScannerV2(this, cacheBlocks, pread, isCompaction);
}
/**
* Retrieve block from cache. Validates the retrieved block's type vs {@code expectedBlockType}
* and its encoding vs. {@code expectedDataBlockEncoding}. Unpacks the block as necessary.
*/
private HFileBlock getCachedBlock(BlockCacheKey cacheKey, boolean cacheBlock, boolean useLock,
boolean isCompaction, boolean updateCacheMetrics, BlockType expectedBlockType,
DataBlockEncoding expectedDataBlockEncoding) throws IOException {
// Check cache for block. If found return.
if (cacheConf.isBlockCacheEnabled()) {
BlockCache cache = cacheConf.getBlockCache();
HFileBlock cachedBlock = (HFileBlock) cache.getBlock(cacheKey, cacheBlock, useLock,
updateCacheMetrics);
if (cachedBlock != null) {
if (cacheConf.shouldCacheCompressed(cachedBlock.getBlockType().getCategory())) {
cachedBlock = cachedBlock.unpack(hfileContext, fsBlockReader);
}
validateBlockType(cachedBlock, expectedBlockType);
if (expectedDataBlockEncoding == null) {
return cachedBlock;
}
DataBlockEncoding actualDataBlockEncoding =
cachedBlock.getDataBlockEncoding();
// Block types other than data blocks always have
// DataBlockEncoding.NONE. To avoid false negative cache misses, only
// perform this check if cached block is a data block.
if (cachedBlock.getBlockType().isData() &&
!actualDataBlockEncoding.equals(expectedDataBlockEncoding)) {
// This mismatch may happen if a ScannerV2, which is used for say a
// compaction, tries to read an encoded block from the block cache.
// The reverse might happen when an EncodedScannerV2 tries to read
// un-encoded blocks which were cached earlier.
//
// Because returning a data block with an implicit BlockType mismatch
// will cause the requesting scanner to throw a disk read should be
// forced here. This will potentially cause a significant number of
// cache misses, so update so we should keep track of this as it might
// justify the work on a CompoundScannerV2.
if (!expectedDataBlockEncoding.equals(DataBlockEncoding.NONE) &&
!actualDataBlockEncoding.equals(DataBlockEncoding.NONE)) {
// If the block is encoded but the encoding does not match the
// expected encoding it is likely the encoding was changed but the
// block was not yet evicted. Evictions on file close happen async
// so blocks with the old encoding still linger in cache for some
// period of time. This event should be rare as it only happens on
// schema definition change.
LOG.info("Evicting cached block with key " + cacheKey +
" because of a data block encoding mismatch" +
"; expected: " + expectedDataBlockEncoding +
", actual: " + actualDataBlockEncoding);
cache.evictBlock(cacheKey);
}
return null;
}
return cachedBlock;
}
}
return null;
}
/**
* @param metaBlockName
* @param cacheBlock Add block to cache, if found
* @return block wrapped in a ByteBuffer, with header skipped
* @throws IOException
*/
@Override
public ByteBuffer getMetaBlock(String metaBlockName, boolean cacheBlock)
throws IOException {
if (trailer.getMetaIndexCount() == 0) {
return null; // there are no meta blocks
}
if (metaBlockIndexReader == null) {
throw new IOException("Meta index not loaded");
}
byte[] mbname = Bytes.toBytes(metaBlockName);
int block = metaBlockIndexReader.rootBlockContainingKey(mbname,
0, mbname.length);
if (block == -1)
return null;
long blockSize = metaBlockIndexReader.getRootBlockDataSize(block);
// Per meta key from any given file, synchronize reads for said block. This
// is OK to do for meta blocks because the meta block index is always
// single-level.
synchronized (metaBlockIndexReader.getRootBlockKey(block)) {
// Check cache for block. If found return.
long metaBlockOffset = metaBlockIndexReader.getRootBlockOffset(block);
BlockCacheKey cacheKey = new BlockCacheKey(name, metaBlockOffset,
this.isPrimaryReplicaReader(), BlockType.META);
cacheBlock &= cacheConf.shouldCacheDataOnRead();
if (cacheConf.isBlockCacheEnabled()) {
HFileBlock cachedBlock = getCachedBlock(cacheKey, cacheBlock, false, true, true,
BlockType.META, null);
if (cachedBlock != null) {
assert cachedBlock.isUnpacked() : "Packed block leak.";
// Return a distinct 'shallow copy' of the block,
// so pos does not get messed by the scanner
return cachedBlock.getBufferWithoutHeader();
}
// Cache Miss, please load.
}
HFileBlock metaBlock = fsBlockReader.readBlockData(metaBlockOffset,
blockSize, true).unpack(hfileContext, fsBlockReader);
// Cache the block
if (cacheBlock) {
cacheConf.getBlockCache().cacheBlock(cacheKey, metaBlock,
cacheConf.isInMemory(), this.cacheConf.isCacheDataInL1());
}
return metaBlock.getBufferWithoutHeader();
}
}
@Override
public HFileBlock readBlock(long dataBlockOffset, long onDiskBlockSize,
final boolean cacheBlock, boolean pread, final boolean isCompaction,
boolean updateCacheMetrics, BlockType expectedBlockType,
DataBlockEncoding expectedDataBlockEncoding)
throws IOException {
if (dataBlockIndexReader == null) {
throw new IOException("Block index not loaded");
}
long trailerOffset = trailer.getLoadOnOpenDataOffset();
if (dataBlockOffset < 0 || dataBlockOffset >= trailerOffset) {
throw new IOException("Requested block is out of range: " + dataBlockOffset +
", lastDataBlockOffset: " + trailer.getLastDataBlockOffset() +
", trailer.getLoadOnOpenDataOffset: " + trailerOffset);
}
// For any given block from any given file, synchronize reads for said block.
// Without a cache, this synchronizing is needless overhead, but really
// the other choice is to duplicate work (which the cache would prevent you
// from doing).
BlockCacheKey cacheKey =
new BlockCacheKey(name, dataBlockOffset, this.isPrimaryReplicaReader(), expectedBlockType);
boolean useLock = false;
IdLock.Entry lockEntry = null;
TraceScope traceScope = Trace.startSpan("HFileReaderV2.readBlock");
try {
while (true) {
// Check cache for block. If found return.
if (cacheConf.shouldReadBlockFromCache(expectedBlockType)) {
if (useLock) {
lockEntry = offsetLock.getLockEntry(dataBlockOffset);
}
// Try and get the block from the block cache. If the useLock variable is true then this
// is the second time through the loop and it should not be counted as a block cache miss.
HFileBlock cachedBlock = getCachedBlock(cacheKey, cacheBlock, useLock, isCompaction,
updateCacheMetrics, expectedBlockType, expectedDataBlockEncoding);
if (cachedBlock != null) {
if (Trace.isTracing()) {
traceScope.getSpan().addTimelineAnnotation("blockCacheHit");
}
assert cachedBlock.isUnpacked() : "Packed block leak.";
if (cachedBlock.getBlockType().isData()) {
if (updateCacheMetrics) {
HFile.DATABLOCK_READ_COUNT.increment();
}
// Validate encoding type for data blocks. We include encoding
// type in the cache key, and we expect it to match on a cache hit.
if (cachedBlock.getDataBlockEncoding() != dataBlockEncoder.getDataBlockEncoding()) {
throw new IOException("Cached block under key " + cacheKey + " "
+ "has wrong encoding: " + cachedBlock.getDataBlockEncoding() + " (expected: "
+ dataBlockEncoder.getDataBlockEncoding() + ")");
}
}
// Cache-hit. Return!
return cachedBlock;
}
if (!useLock && cacheBlock && cacheConf.shouldLockOnCacheMiss(expectedBlockType)) {
// check cache again with lock
useLock = true;
continue;
}
// Carry on, please load.
}
if (Trace.isTracing()) {
traceScope.getSpan().addTimelineAnnotation("blockCacheMiss");
}
// Load block from filesystem.
HFileBlock hfileBlock = fsBlockReader.readBlockData(dataBlockOffset, onDiskBlockSize,
pread);
validateBlockType(hfileBlock, expectedBlockType);
HFileBlock unpacked = hfileBlock.unpack(hfileContext, fsBlockReader);
BlockType.BlockCategory category = hfileBlock.getBlockType().getCategory();
// Cache the block if necessary
if (cacheBlock && cacheConf.shouldCacheBlockOnRead(category)) {
cacheConf.getBlockCache().cacheBlock(cacheKey,
cacheConf.shouldCacheCompressed(category) ? hfileBlock : unpacked,
cacheConf.isInMemory(), this.cacheConf.isCacheDataInL1());
}
if (updateCacheMetrics && hfileBlock.getBlockType().isData()) {
HFile.DATABLOCK_READ_COUNT.increment();
}
return unpacked;
}
} finally {
traceScope.close();
if (lockEntry != null) {
offsetLock.releaseLockEntry(lockEntry);
}
}
}
@Override
public boolean hasMVCCInfo() {
return includesMemstoreTS && decodeMemstoreTS;
}
/**
* Compares the actual type of a block retrieved from cache or disk with its
* expected type and throws an exception in case of a mismatch. Expected
* block type of {@link BlockType#DATA} is considered to match the actual
* block type [@link {@link BlockType#ENCODED_DATA} as well.
* @param block a block retrieved from cache or disk
* @param expectedBlockType the expected block type, or null to skip the
* check
*/
private void validateBlockType(HFileBlock block,
BlockType expectedBlockType) throws IOException {
if (expectedBlockType == null) {
return;
}
BlockType actualBlockType = block.getBlockType();
if (expectedBlockType.isData() && actualBlockType.isData()) {
// We consider DATA to match ENCODED_DATA for the purpose of this
// verification.
return;
}
if (actualBlockType != expectedBlockType) {
throw new IOException("Expected block type " + expectedBlockType + ", " +
"but got " + actualBlockType + ": " + block);
}
}
/**
* @return Last key in the file. May be null if file has no entries. Note that
* this is not the last row key, but rather the byte form of the last
* KeyValue.
*/
@Override
public byte[] getLastKey() {
return dataBlockIndexReader.isEmpty() ? null : lastKey;
}
/**
* @return Midkey for this file. We work with block boundaries only so
* returned midkey is an approximation only.
* @throws IOException
*/
@Override
public byte[] midkey() throws IOException {
return dataBlockIndexReader.midkey();
}
@Override
public void close() throws IOException {
close(cacheConf.shouldEvictOnClose());
}
public void close(boolean evictOnClose) throws IOException {
PrefetchExecutor.cancel(path);
if (evictOnClose && cacheConf.isBlockCacheEnabled()) {
int numEvicted = cacheConf.getBlockCache().evictBlocksByHfileName(name);
if (LOG.isTraceEnabled()) {
LOG.trace("On close, file=" + name + " evicted=" + numEvicted
+ " block(s)");
}
}
fsBlockReader.closeStreams();
}
public DataBlockEncoding getEffectiveEncodingInCache(boolean isCompaction) {
return dataBlockEncoder.getEffectiveEncodingInCache(isCompaction);
}
/** For testing */
@Override
HFileBlock.FSReader getUncachedBlockReader() {
return fsBlockReader;
}
protected abstract static class AbstractScannerV2
extends AbstractHFileReader.Scanner {
protected HFileBlock block;
@Override
public Cell getNextIndexedKey() {
return nextIndexedKey;
}
/**
* The next indexed key is to keep track of the indexed key of the next data block.
* If the nextIndexedKey is HConstants.NO_NEXT_INDEXED_KEY, it means that the
* current data block is the last data block.
*
* If the nextIndexedKey is null, it means the nextIndexedKey has not been loaded yet.
*/
protected Cell nextIndexedKey;
public AbstractScannerV2(HFileReaderV2 r, boolean cacheBlocks,
final boolean pread, final boolean isCompaction) {
super(r, cacheBlocks, pread, isCompaction);
}
protected abstract ByteBuffer getFirstKeyInBlock(HFileBlock curBlock);
protected abstract int loadBlockAndSeekToKey(HFileBlock seekToBlock, Cell nextIndexedKey,
boolean rewind, Cell key, boolean seekBefore) throws IOException;
@Override
public int seekTo(byte[] key, int offset, int length) throws IOException {
// Always rewind to the first key of the block, because the given key
// might be before or after the current key.
return seekTo(new KeyValue.KeyOnlyKeyValue(key, offset, length));
}
@Override
public int reseekTo(byte[] key, int offset, int length) throws IOException {
return reseekTo(new KeyValue.KeyOnlyKeyValue(key, offset, length));
}
@Override
public int seekTo(Cell key) throws IOException {
return seekTo(key, true);
}
@Override
public int reseekTo(Cell key) throws IOException {
int compared;
if (isSeeked()) {
compared = compareKey(reader.getComparator(), key);
if (compared < 1) {
// If the required key is less than or equal to current key, then
// don't do anything.
return compared;
} else {
// The comparison with no_next_index_key has to be checked
if (this.nextIndexedKey != null &&
(this.nextIndexedKey == KeyValueScanner.NO_NEXT_INDEXED_KEY || reader
.getComparator()
.compareOnlyKeyPortion(key, nextIndexedKey) < 0)) {
// The reader shall continue to scan the current data block instead
// of querying the
// block index as long as it knows the target key is strictly
// smaller than
// the next indexed key or the current data block is the last data
// block.
return loadBlockAndSeekToKey(this.block, nextIndexedKey, false, key, false);
}
}
}
// Don't rewind on a reseek operation, because reseek implies that we are
// always going forward in the file.
return seekTo(key, false);
}
/**
* An internal API function. Seek to the given key, optionally rewinding to
* the first key of the block before doing the seek.
*
* @param key - a cell representing the key that we need to fetch
* @param rewind whether to rewind to the first key of the block before
* doing the seek. If this is false, we are assuming we never go
* back, otherwise the result is undefined.
* @return -1 if the key is earlier than the first key of the file,
* 0 if we are at the given key, 1 if we are past the given key
* -2 if the key is earlier than the first key of the file while
* using a faked index key
* @throws IOException
*/
public int seekTo(Cell key, boolean rewind) throws IOException {
HFileBlockIndex.BlockIndexReader indexReader = reader.getDataBlockIndexReader();
BlockWithScanInfo blockWithScanInfo = indexReader.loadDataBlockWithScanInfo(key, block,
cacheBlocks, pread, isCompaction, getEffectiveDataBlockEncoding());
if (blockWithScanInfo == null || blockWithScanInfo.getHFileBlock() == null) {
// This happens if the key e.g. falls before the beginning of the file.
return -1;
}
return loadBlockAndSeekToKey(blockWithScanInfo.getHFileBlock(),
blockWithScanInfo.getNextIndexedKey(), rewind, key, false);
}
@Override
public boolean seekBefore(byte[] key, int offset, int length) throws IOException {
return seekBefore(new KeyValue.KeyOnlyKeyValue(key, offset, length));
}
@Override
public boolean seekBefore(Cell key) throws IOException {
HFileBlock seekToBlock = reader.getDataBlockIndexReader().seekToDataBlock(key, block,
cacheBlocks, pread, isCompaction,
((HFileReaderV2) reader).getEffectiveEncodingInCache(isCompaction));
if (seekToBlock == null) {
return false;
}
ByteBuffer firstKey = getFirstKeyInBlock(seekToBlock);
if (reader.getComparator()
.compareOnlyKeyPortion(
new KeyValue.KeyOnlyKeyValue(firstKey.array(), firstKey.arrayOffset(),
firstKey.limit()), key) >= 0) {
long previousBlockOffset = seekToBlock.getPrevBlockOffset();
// The key we are interested in
if (previousBlockOffset == -1) {
// we have a 'problem', the key we want is the first of the file.
return false;
}
// It is important that we compute and pass onDiskSize to the block
// reader so that it does not have to read the header separately to
// figure out the size. Currently, we do not have a way to do this
// correctly in the general case however.
// TODO: See https://issues.apache.org/jira/browse/HBASE-14576
int prevBlockSize = -1;
seekToBlock = reader.readBlock(previousBlockOffset,
prevBlockSize, cacheBlocks,
pread, isCompaction, true, BlockType.DATA, getEffectiveDataBlockEncoding());
// TODO shortcut: seek forward in this block to the last key of the
// block.
}
Cell firstKeyInCurrentBlock = new KeyValue.KeyOnlyKeyValue(Bytes.getBytes(firstKey));
loadBlockAndSeekToKey(seekToBlock, firstKeyInCurrentBlock, true, key, true);
return true;
}
/**
* Scans blocks in the "scanned" section of the {@link HFile} until the next
* data block is found.
*
* @return the next block, or null if there are no more data blocks
* @throws IOException
*/
@edu.umd.cs.findbugs.annotations.SuppressWarnings(value="NP_NULL_ON_SOME_PATH",
justification="Yeah, unnecessary null check; could do w/ clean up")
protected HFileBlock readNextDataBlock() throws IOException {
long lastDataBlockOffset = reader.getTrailer().getLastDataBlockOffset();
if (block == null)
return null;
HFileBlock curBlock = block;
do {
if (curBlock.getOffset() >= lastDataBlockOffset) {
return null;
}
if (curBlock.getOffset() < 0) {
throw new IOException("Invalid block file offset: " + block);
}
// We are reading the next block without block type validation, because
// it might turn out to be a non-data block.
curBlock = reader.readBlock(curBlock.getOffset()
+ curBlock.getOnDiskSizeWithHeader(),
curBlock.getNextBlockOnDiskSize(), cacheBlocks, pread,
isCompaction, true, null, getEffectiveDataBlockEncoding());
} while (!curBlock.getBlockType().isData());
return curBlock;
}
public DataBlockEncoding getEffectiveDataBlockEncoding() {
return ((HFileReaderV2)reader).getEffectiveEncodingInCache(isCompaction);
}
/**
* Compare the given key against the current key
* @param comparator
* @param key
* @param offset
* @param length
* @return -1 is the passed key is smaller than the current key, 0 if equal and 1 if greater
*/
public abstract int compareKey(KVComparator comparator, byte[] key, int offset,
int length);
public abstract int compareKey(KVComparator comparator, Cell kv);
}
/**
* Implementation of {@link HFileScanner} interface.
*/
protected static class ScannerV2 extends AbstractScannerV2 {
private HFileReaderV2 reader;
public ScannerV2(HFileReaderV2 r, boolean cacheBlocks,
final boolean pread, final boolean isCompaction) {
super(r, cacheBlocks, pread, isCompaction);
this.reader = r;
}
@Override
public Cell getKeyValue() {
if (!isSeeked())
return null;
return formNoTagsKeyValue();
}
protected Cell formNoTagsKeyValue() {
NoTagsKeyValue ret = new NoTagsKeyValue(blockBuffer.array(), blockBuffer.arrayOffset()
+ blockBuffer.position(), getCellBufSize());
if (this.reader.shouldIncludeMemstoreTS()) {
ret.setSequenceId(currMemstoreTS);
}
return ret;
}
protected int getCellBufSize() {
return KEY_VALUE_LEN_SIZE + currKeyLen + currValueLen;
}
@Override
public ByteBuffer getKey() {
assertSeeked();
return ByteBuffer.wrap(
blockBuffer.array(),
blockBuffer.arrayOffset() + blockBuffer.position()
+ KEY_VALUE_LEN_SIZE, currKeyLen).slice();
}
@Override
public int compareKey(KVComparator comparator, byte[] key, int offset, int length) {
return comparator.compareFlatKey(key, offset, length, blockBuffer.array(),
blockBuffer.arrayOffset() + blockBuffer.position() + KEY_VALUE_LEN_SIZE, currKeyLen);
}
@Override
public ByteBuffer getValue() {
assertSeeked();
return ByteBuffer.wrap(
blockBuffer.array(),
blockBuffer.arrayOffset() + blockBuffer.position()
+ KEY_VALUE_LEN_SIZE + currKeyLen, currValueLen).slice();
}
protected void setNonSeekedState() {
block = null;
blockBuffer = null;
currKeyLen = 0;
currValueLen = 0;
currMemstoreTS = 0;
currMemstoreTSLen = 0;
}
/**
* Set the position on current backing blockBuffer.
*/
private void positionThisBlockBuffer() {
try {
blockBuffer.position(getNextCellStartPosition());
} catch (IllegalArgumentException e) {
LOG.error("Current pos = " + blockBuffer.position()
+ "; currKeyLen = " + currKeyLen + "; currValLen = "
+ currValueLen + "; block limit = " + blockBuffer.limit()
+ "; HFile name = " + reader.getName()
+ "; currBlock currBlockOffset = " + block.getOffset());
throw e;
}
}
/**
* Set our selves up for the next 'next' invocation, set up next block.
* @return True is more to read else false if at the end.
* @throws IOException
*/
private boolean positionForNextBlock() throws IOException {
// Methods are small so they get inlined because they are 'hot'.
long lastDataBlockOffset = reader.getTrailer().getLastDataBlockOffset();
if (block.getOffset() >= lastDataBlockOffset) {
setNonSeekedState();
return false;
}
return isNextBlock();
}
private boolean isNextBlock() throws IOException {
// Methods are small so they get inlined because they are 'hot'.
HFileBlock nextBlock = readNextDataBlock();
if (nextBlock == null) {
setNonSeekedState();
return false;
}
updateCurrBlock(nextBlock);
return true;
}
private final boolean _next() throws IOException {
// Small method so can be inlined. It is a hot one.
if (blockBuffer.remaining() <= 0) {
return positionForNextBlock();
}
// We are still in the same block.
readKeyValueLen();
return true;
}
/**
* Go to the next key/value in the block section. Loads the next block if
* necessary. If successful, {@link #getKey()} and {@link #getValue()} can
* be called.
*
* @return true if successfully navigated to the next key/value
*/
@Override
public boolean next() throws IOException {
// This is a hot method so extreme measures taken to ensure it is small and inlineable.
// Checked by setting: -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlining -XX:+PrintCompilation
assertSeeked();
positionThisBlockBuffer();
return _next();
}
protected int getNextCellStartPosition() {
return blockBuffer.position() + KEY_VALUE_LEN_SIZE + currKeyLen + currValueLen
+ currMemstoreTSLen;
}
/**
* Positions this scanner at the start of the file.
*
* @return false if empty file; i.e. a call to next would return false and
* the current key and value are undefined.
* @throws IOException
*/
@Override
public boolean seekTo() throws IOException {
if (reader == null) {
return false;
}
if (reader.getTrailer().getEntryCount() == 0) {
// No data blocks.
return false;
}
long firstDataBlockOffset =
reader.getTrailer().getFirstDataBlockOffset();
if (block != null && block.getOffset() == firstDataBlockOffset) {
blockBuffer.rewind();
readKeyValueLen();
return true;
}
block = reader.readBlock(firstDataBlockOffset, -1, cacheBlocks, pread,
isCompaction, true, BlockType.DATA, getEffectiveDataBlockEncoding());
if (block.getOffset() < 0) {
throw new IOException("Invalid block offset: " + block.getOffset());
}
updateCurrBlock(block);
return true;
}
@Override
protected int loadBlockAndSeekToKey(HFileBlock seekToBlock, Cell nextIndexedKey,
boolean rewind, Cell key, boolean seekBefore) throws IOException {
if (block == null || block.getOffset() != seekToBlock.getOffset()) {
updateCurrBlock(seekToBlock);
} else if (rewind) {
blockBuffer.rewind();
}
// Update the nextIndexedKey
this.nextIndexedKey = nextIndexedKey;
return blockSeek(key, seekBefore);
}
/**
* Updates the current block to be the given {@link HFileBlock}. Seeks to
* the the first key/value pair.
*
* @param newBlock the block to make current
*/
protected void updateCurrBlock(HFileBlock newBlock) {
block = newBlock;
// sanity check
if (block.getBlockType() != BlockType.DATA) {
throw new IllegalStateException("ScannerV2 works only on data " +
"blocks, got " + block.getBlockType() + "; " +
"fileName=" + reader.name + ", " +
"dataBlockEncoder=" + reader.dataBlockEncoder + ", " +
"isCompaction=" + isCompaction);
}
blockBuffer = block.getBufferWithoutHeader();
readKeyValueLen();
blockFetches.incrementAndGet();
// Reset the next indexed key
this.nextIndexedKey = null;
}
/**
* @param v
* @return True if v < 0 or v > current block buffer limit.
*/
protected final boolean checkLen(final int v) {
return v < 0 || v > this.blockBuffer.limit();
}
/**
* Check key and value lengths are wholesome.
*/
protected final void checkKeyValueLen() {
if (checkLen(this.currKeyLen) || checkLen(this.currValueLen)) {
throw new IllegalStateException("Invalid currKeyLen " + this.currKeyLen +
" or currValueLen " + this.currValueLen + ". Block offset: " + block.getOffset() +
", block length: " + this.blockBuffer.limit() + ", position: " +
this.blockBuffer.position() + " (without header).");
}
}
protected void readKeyValueLen() {
// TODO: METHOD (mostly) DUPLICATED IN V3!!!!! FIXED in master branch by collapsing v3 and v2.
// This is a hot method. We go out of our way to make this method short so it can be
// inlined and is not too big to compile. We also manage position in ByteBuffer ourselves
// because it is faster than going via range-checked ByteBuffer methods or going through a
// byte buffer array a byte at a time.
int p = blockBuffer.position() + blockBuffer.arrayOffset();
// Get a long at a time rather than read two individual ints. In micro-benchmarking, even
// with the extra bit-fiddling, this is order-of-magnitude faster than getting two ints.
long ll = Bytes.toLong(blockBuffer.array(), p);
// Read top half as an int of key length and bottom int as value length
this.currKeyLen = (int)(ll >> Integer.SIZE);
this.currValueLen = (int)(Bytes.MASK_FOR_LOWER_INT_IN_LONG ^ ll);
checkKeyValueLen();
// Move position past the key and value lengths and then beyond the key and value
p += (Bytes.SIZEOF_LONG + currKeyLen + currValueLen);
readMvccVersion(p);
}
/**
* Read mvcc. Does checks to see if we even need to read the mvcc at all.
* @param position
*/
protected void readMvccVersion(final int position) {
// See if we even need to decode mvcc.
if (!this.reader.shouldIncludeMemstoreTS()) return;
if (!this.reader.decodeMemstoreTS) {
currMemstoreTS = 0;
currMemstoreTSLen = 1;
return;
}
_readMvccVersion(position);
}
/**
* Actually do the mvcc read. Does no checks.
* @param position
*/
private void _readMvccVersion(final int position) {
// This is Bytes#bytesToVint inlined so can save a few instructions in this hot method; i.e.
// previous if one-byte vint, we'd redo the vint call to find int size.
// Also the method is kept small so can be inlined.
byte firstByte = blockBuffer.array()[position];
int len = WritableUtils.decodeVIntSize(firstByte);
if (len == 1) {
this.currMemstoreTS = firstByte;
} else {
long i = 0;
for (int idx = 0; idx < len - 1; idx++) {
byte b = blockBuffer.array()[position + 1 + idx];
i = i << 8;
i = i | (b & 0xFF);
}
currMemstoreTS = (WritableUtils.isNegativeVInt(firstByte) ? ~i : i);
}
this.currMemstoreTSLen = len;
}
protected void readMvccVersion() {
// TODO CLEANUP!!!
readMvccVersion(blockBuffer.arrayOffset() + blockBuffer.position());
}
/**
* Within a loaded block, seek looking for the last key that is smaller than
* (or equal to?) the key we are interested in.
*
* A note on the seekBefore: if you have seekBefore = true, AND the first
* key in the block = key, then you'll get thrown exceptions. The caller has
* to check for that case and load the previous block as appropriate.
*
* @param key
* the key to find
* @param seekBefore
* find the key before the given key in case of exact match.
* @return 0 in case of an exact key match, 1 in case of an inexact match,
* -2 in case of an inexact match and furthermore, the input key
* less than the first key of current block(e.g. using a faked index
* key)
*/
protected int blockSeek(Cell key, boolean seekBefore) {
int klen, vlen;
long memstoreTS = 0;
int memstoreTSLen = 0;
int lastKeyValueSize = -1;
KeyValue.KeyOnlyKeyValue keyOnlykv = new KeyValue.KeyOnlyKeyValue();
do {
blockBuffer.mark();
klen = blockBuffer.getInt();
vlen = blockBuffer.getInt();
blockBuffer.reset();
if (this.reader.shouldIncludeMemstoreTS()) {
if (this.reader.decodeMemstoreTS) {
int memstoreTSOffset = blockBuffer.arrayOffset() + blockBuffer.position()
+ KEY_VALUE_LEN_SIZE + klen + vlen;
memstoreTS = Bytes.readAsVLong(blockBuffer.array(), memstoreTSOffset);
memstoreTSLen = WritableUtils.getVIntSize(memstoreTS);
} else {
memstoreTS = 0;
memstoreTSLen = 1;
}
}
int keyOffset = blockBuffer.arrayOffset() + blockBuffer.position() + KEY_VALUE_LEN_SIZE;
keyOnlykv.setKey(blockBuffer.array(), keyOffset, klen);
int comp = reader.getComparator().compareOnlyKeyPortion(key, keyOnlykv);
if (comp == 0) {
if (seekBefore) {
if (lastKeyValueSize < 0) {
throw new IllegalStateException("blockSeek with seekBefore "
+ "at the first key of the block: key="
+ CellUtil.getCellKeyAsString(key)
+ ", blockOffset=" + block.getOffset() + ", onDiskSize="
+ block.getOnDiskSizeWithHeader());
}
blockBuffer.position(blockBuffer.position() - lastKeyValueSize);
readKeyValueLen();
return 1; // non exact match.
}
currKeyLen = klen;
currValueLen = vlen;
if (this.reader.shouldIncludeMemstoreTS()) {
currMemstoreTS = memstoreTS;
currMemstoreTSLen = memstoreTSLen;
}
return 0; // indicate exact match
} else if (comp < 0) {
if (lastKeyValueSize > 0)
blockBuffer.position(blockBuffer.position() - lastKeyValueSize);
readKeyValueLen();
if (lastKeyValueSize == -1 && blockBuffer.position() == 0
&& this.reader.trailer.getMinorVersion() >= MINOR_VERSION_WITH_FAKED_KEY) {
return HConstants.INDEX_KEY_MAGIC;
}
return 1;
}
// The size of this key/value tuple, including key/value length fields.
lastKeyValueSize = klen + vlen + memstoreTSLen + KEY_VALUE_LEN_SIZE;
blockBuffer.position(blockBuffer.position() + lastKeyValueSize);
} while (blockBuffer.remaining() > 0);
// Seek to the last key we successfully read. This will happen if this is
// the last key/value pair in the file, in which case the following call
// to next() has to return false.
blockBuffer.position(blockBuffer.position() - lastKeyValueSize);
readKeyValueLen();
return 1; // didn't exactly find it.
}
@Override
protected ByteBuffer getFirstKeyInBlock(HFileBlock curBlock) {
ByteBuffer buffer = curBlock.getBufferWithoutHeader();
// It is safe to manipulate this buffer because we own the buffer object.
buffer.rewind();
int klen = buffer.getInt();
buffer.getInt();
ByteBuffer keyBuff = buffer.slice();
keyBuff.limit(klen);
keyBuff.rewind();
return keyBuff;
}
@Override
public String getKeyString() {
return Bytes.toStringBinary(blockBuffer.array(),
blockBuffer.arrayOffset() + blockBuffer.position()
+ KEY_VALUE_LEN_SIZE, currKeyLen);
}
@Override
public String getValueString() {
return Bytes.toString(blockBuffer.array(), blockBuffer.arrayOffset()
+ blockBuffer.position() + KEY_VALUE_LEN_SIZE + currKeyLen,
currValueLen);
}
@Override
public int compareKey(KVComparator comparator, Cell key) {
return comparator.compareOnlyKeyPortion(
key,
new KeyValue.KeyOnlyKeyValue(blockBuffer.array(), blockBuffer.arrayOffset()
+ blockBuffer.position() + KEY_VALUE_LEN_SIZE, currKeyLen));
}
}
/**
* ScannerV2 that operates on encoded data blocks.
*/
protected static class EncodedScannerV2 extends AbstractScannerV2 {
private final HFileBlockDecodingContext decodingCtx;
private final DataBlockEncoder.EncodedSeeker seeker;
private final DataBlockEncoder dataBlockEncoder;
protected final HFileContext meta;
public EncodedScannerV2(HFileReaderV2 reader, boolean cacheBlocks,
boolean pread, boolean isCompaction, HFileContext meta) {
super(reader, cacheBlocks, pread, isCompaction);
DataBlockEncoding encoding = reader.dataBlockEncoder.getDataBlockEncoding();
dataBlockEncoder = encoding.getEncoder();
decodingCtx = dataBlockEncoder.newDataBlockDecodingContext(meta);
seeker = dataBlockEncoder.createSeeker(
reader.getComparator(), decodingCtx);
this.meta = meta;
}
@Override
public boolean isSeeked(){
return this.block != null;
}
/**
* Updates the current block to be the given {@link HFileBlock}. Seeks to
* the the first key/value pair.
*
* @param newBlock the block to make current
* @throws CorruptHFileException
*/
private void updateCurrentBlock(HFileBlock newBlock) throws CorruptHFileException {
block = newBlock;
// sanity checks
if (block.getBlockType() != BlockType.ENCODED_DATA) {
throw new IllegalStateException(
"EncodedScanner works only on encoded data blocks");
}
short dataBlockEncoderId = block.getDataBlockEncodingId();
if (!DataBlockEncoding.isCorrectEncoder(dataBlockEncoder, dataBlockEncoderId)) {
String encoderCls = dataBlockEncoder.getClass().getName();
throw new CorruptHFileException("Encoder " + encoderCls
+ " doesn't support data block encoding "
+ DataBlockEncoding.getNameFromId(dataBlockEncoderId));
}
seeker.setCurrentBuffer(getEncodedBuffer(newBlock));
blockFetches.incrementAndGet();
// Reset the next indexed key
this.nextIndexedKey = null;
}
private ByteBuffer getEncodedBuffer(HFileBlock newBlock) {
ByteBuffer origBlock = newBlock.getBufferReadOnly();
ByteBuffer encodedBlock = ByteBuffer.wrap(origBlock.array(),
origBlock.arrayOffset() + newBlock.headerSize() +
DataBlockEncoding.ID_SIZE,
newBlock.getUncompressedSizeWithoutHeader() -
DataBlockEncoding.ID_SIZE).slice();
return encodedBlock;
}
@Override
public boolean seekTo() throws IOException {
if (reader == null) {
return false;
}
if (reader.getTrailer().getEntryCount() == 0) {
// No data blocks.
return false;
}
long firstDataBlockOffset =
reader.getTrailer().getFirstDataBlockOffset();
if (block != null && block.getOffset() == firstDataBlockOffset) {
seeker.rewind();
return true;
}
block = reader.readBlock(firstDataBlockOffset, -1, cacheBlocks, pread,
isCompaction, true, BlockType.DATA, getEffectiveDataBlockEncoding());
if (block.getOffset() < 0) {
throw new IOException("Invalid block offset: " + block.getOffset());
}
updateCurrentBlock(block);
return true;
}
@Override
public boolean next() throws IOException {
boolean isValid = seeker.next();
if (!isValid) {
block = readNextDataBlock();
isValid = block != null;
if (isValid) {
updateCurrentBlock(block);
}
}
return isValid;
}
@Override
public ByteBuffer getKey() {
assertValidSeek();
return seeker.getKeyDeepCopy();
}
@Override
public int compareKey(KVComparator comparator, byte[] key, int offset, int length) {
return seeker.compareKey(comparator, key, offset, length);
}
@Override
public ByteBuffer getValue() {
assertValidSeek();
return seeker.getValueShallowCopy();
}
@Override
public Cell getKeyValue() {
if (block == null) {
return null;
}
return seeker.getKeyValue();
}
@Override
public String getKeyString() {
ByteBuffer keyBuffer = getKey();
return Bytes.toStringBinary(keyBuffer.array(),
keyBuffer.arrayOffset(), keyBuffer.limit());
}
@Override
public String getValueString() {
ByteBuffer valueBuffer = getValue();
return Bytes.toStringBinary(valueBuffer.array(),
valueBuffer.arrayOffset(), valueBuffer.limit());
}
private void assertValidSeek() {
if (block == null) {
throw new NotSeekedException();
}
}
@Override
protected ByteBuffer getFirstKeyInBlock(HFileBlock curBlock) {
return dataBlockEncoder.getFirstKeyInBlock(getEncodedBuffer(curBlock));
}
@Override
protected int loadBlockAndSeekToKey(HFileBlock seekToBlock, Cell nextIndexedKey,
boolean rewind, Cell key, boolean seekBefore) throws IOException {
if (block == null || block.getOffset() != seekToBlock.getOffset()) {
updateCurrentBlock(seekToBlock);
} else if (rewind) {
seeker.rewind();
}
this.nextIndexedKey = nextIndexedKey;
return seeker.seekToKeyInBlock(key, seekBefore);
}
@Override
public int compareKey(KVComparator comparator, Cell key) {
return seeker.compareKey(comparator, key);
}
}
/**
* Returns a buffer with the Bloom filter metadata. The caller takes
* ownership of the buffer.
*/
@Override
public DataInput getGeneralBloomFilterMetadata() throws IOException {
return this.getBloomFilterMetadata(BlockType.GENERAL_BLOOM_META);
}
@Override
public DataInput getDeleteBloomFilterMetadata() throws IOException {
return this.getBloomFilterMetadata(BlockType.DELETE_FAMILY_BLOOM_META);
}
private DataInput getBloomFilterMetadata(BlockType blockType)
throws IOException {
if (blockType != BlockType.GENERAL_BLOOM_META &&
blockType != BlockType.DELETE_FAMILY_BLOOM_META) {
throw new RuntimeException("Block Type: " + blockType.toString() +
" is not supported") ;
}
for (HFileBlock b : loadOnOpenBlocks)
if (b.getBlockType() == blockType)
return b.getByteStream();
return null;
}
@Override
public boolean isFileInfoLoaded() {
return true; // We load file info in constructor in version 2.
}
/**
* Validates that the minor version is within acceptable limits.
* Otherwise throws an Runtime exception
*/
private void validateMinorVersion(Path path, int minorVersion) {
if (minorVersion < MIN_MINOR_VERSION ||
minorVersion > MAX_MINOR_VERSION) {
String msg = "Minor version for path " + path +
" is expected to be between " +
MIN_MINOR_VERSION + " and " + MAX_MINOR_VERSION +
" but is found to be " + minorVersion;
LOG.error(msg);
throw new RuntimeException(msg);
}
}
@Override
public int getMajorVersion() {
return 2;
}
@Override
public HFileContext getFileContext() {
return hfileContext;
}
/**
* Returns false if block prefetching was requested for this file and has
* not completed, true otherwise
*/
@VisibleForTesting
boolean prefetchComplete() {
return PrefetchExecutor.isCompleted(path);
}
@Override
public void unbufferStream() {
fsBlockReader.unbufferStream();
}
}